In the field of data input devices, manually operated units, wherein data is input in the form of electronic signals generated through the actuation of various types of data input keyboards, are known in the art. Typically, such devices employ a keyboard or a key pad composed of individual push-button type keys having character indicia permanently associated with each key position to indicate the value or meaning associated with the actuation of each particular key. Incidentally, assemblies using such arrangements are disclosed in U.S. Pat. No. 4,333,090 granted June 1, 1982 and in U.S. patent application Ser. No. 379,755 filed May 19, 1982.
It has also previously been proposed to use sheets of Mylar overlying switch input points and with suitable indications of the location of the switch input points, which may be arranged in a matrix configuration, similar to a key pad. However, the sheet Mylar material is very thin, in the order of a few thousandths of an inch thick, does not resemble a conventional key pad having individual molded keys, and does not have the ruggedness to withstand public usage or adverse environmental conditions.
Also, while data input devices utilizing such Mylar switching assemblies perform satisfactorily when operated by skilled users in controlled environments, such arrangements are not well suited for withstanding the rigorous environments associated with external uses such as those found in the operation of automated bank tellers or building security access systems, which by design may be located in outdoor environments, or may be subject to rain water or spillage from drinks or the like. In external environments, extremes of temperature, humidity and other weather factors, along with problems of vandalism and abuse by the operating public, can render such prior art input devices inoperative. Therefore, it is a primary objective of the present invention to provide a secure data input device that is resistant to the problems associated with operation in a rigorous, noncontrolled environment.